Ecd protect cartilage explants both in hypoxic and normoxic conditions. The Epas 1 gene expression is enhanced under hypoxic condition. With the pre-treatment of 10−8M Ecd, it can effectively eliminate the IL-1β enhanced Epas1 gene expression (A). The Col2a1 gene expression was stationary under normoxic condition (B). Under hypoxic condition, the pretreatment of 10−8M Ecd can effectively eliminate the IL-1β down-regulated Col2a1 gene expression. Under hypoxic condition, IL-1β mediates HIF-2α–induced ADAMTS-5 gene expression of articular cartilage. The pretreatment of 10−8M Ecd can effectively down-regulate MMP3 gene expression only under normoxic condition (C); while down-regulate ADAMTS5 genes expression both in normoxic and hypoxic conditions (D). (Each value is the mean ± standard deviations; n = 8; *:p<0.05; **:p< 0.01; ***:p < 0.001).